The present invention relates to protectors covering saw blades of cutting devices called as “table saws”, in which an upper portion of a saw blade protrudes from an upper surface of a table, on which a workpiece is put.
According to a known table saw, an upper portion of a circular saw blade protrudes from an upper surface of a table, on which a workpiece is put, and cuts the workpiece when the workpiece is moved toward the saw blade along the table. In such a known table saw, a saw blade protector is generally provided in order to prevent other substance than the workpiece from contacting with the saw blade protruding upwardly from the table. The saw blade protector has guard plates covering mainly both right and left sides and upper side of the saw blade, and a mechanism configured to move the guard plates upwardly due to interaction with the workpiece moved toward the saw blade. In general, the guard plates are supported by a holding frame attached to an upper portion of a riving knife such that the guard plates can pivot upwardly and downwardly. It is preferred that the saw blade protector not only can merely pivot upwardly and downwardly, but also be completely removed together with the holding frame for, e.g., easy exchange of the saw blade.
With respect to the table saw, the saw blade rotates in such a direction that a rear side with respect to a cutting direction (i.e., the side of the operator) of the saw blade moves downwardly whereas a front side of the saw blade moves upwardly. Therefore, when the rear side of the saw blade rotating at high speed contacts with cut surfaces of the workpiece right after cutting, the workpiece may be forced to move upwardly (so-called “kickback phenomenon”). In such case, it is difficult to carry out cut process smoothly. Therefore, in a known table saw, a riving knife having the substantially same thickness as the saw blade is provided in front of the saw blade with respect to the cutting direction such that the saw blade and the riving knife are aligned in line. The width between opposite cut surfaces of the workpiece can be held at a predetermined distance by the riving knife positioned between the opposite cut surfaces in order to prevent the cut surfaces from contacting with the saw blade. In addition, kickback prevention claws for preventing the upward movement of the workpiece are disposed on opposite sides of the riving knife such that the kickback prevention claws does not inhibit the movement of the workpiece in the cutting direction during the cutting operation. Similar to the cover structure, the kickback prevention claws are supported by the holding frame.
US2007/0056416A1 (Japanese Laid Open Patent Publications No. 2007-76235) and US2005/0211034A1 (Japanese Laid-Open Patent Publications No. 2005-254671) disclose some techniques with respect to saw blade protectors, riving knives and kickback prevention claws.
The saw blade protectors disclosed in the above patent publications include neither a mechanism for adjusting the height of the holding frame fixed on the upper portion of the riving knife relative to the upper surface of the table nor a mechanism for adjusting inclination of the holding frame in forward and rearward directions with respect to a cutting direction or a direction parallel to the moving direction of a workpiece. Therefore, the inclination of the holding frame with respect to the cutting direction cannot be adjusted depending on, e.g., processing accuracy and assembly accuracy of the related components, and thus, for example, it is not able to accurately control a vertical distance between a rear end of the holding frame (an end close to the operator) with respect to the cutting direction and the upper surface of the table in order to set a covering range of the guard plate for the saw blade.
Therefore, there has been a need for improved saw blade protectors capable of adjusting the position of a holding frame for supporting a guard plate(s) covering a saw blade in order to adjust the relative position of the guard plate(s) to the saw blade.